This invention relates to gas chromatographs and more particularly, to a gas chromatograph and a method of operating it to reseparate trapped components.
Gas chromatographs are extensively used to separate samples into their components. For example, gas chromatographs are used in geochemical analysis of the quantitative distribution of hydrocarbons in crude oils. A crude oil sample is separated by gas chromatography into its components. Typically, each of these components is then burned to CO.sub.2 and the combustion products are analyzed in a mass spectrometer to determine the ratios of the carbon isotopes in each sample. This technique is described in "CORRELATION OF NATURAL GAS BY USE OF CARBON ISOTOPIC DISTRIBUTION BETWEEN HYDROCARBON COMPONENTS" by Alan T. James, American Association of Petroleum Geologists Bulletin, V. 67, No. 7(July 1983). A gas chromatograph-combustion system for performing such analysis is shown in FIG. 2, page 10, of "HYDROUS PYROLYSIS AS A THERMAL ALTERATION SIMULATION TECHNIQUE", Research Report No. 125, February 1983, Energy Resources Group Exploration and Production Research Technology Center, Cities Service Company, Tulsa, Okla.
In such analyses it is extremely important to separate a sample into high purity components. The isotopic concentration of a separated component may be drastically altered if another component is present in even minute amounts. For example when a separation is made between IsoC.sub.4 and normal C.sub.4, even if the amount of normal C.sub.4 contaminating the IsoC.sub.4 cut is less than 1%, this will have a drastic effect on the measurement of the isotope concentrations of the IsoC.sub.4 component.
It is an object of the present invention to provide a gas chromatograph which produces extremely pure components of a sample.